As a method of preparing a magnesium oxide powder, there have been known a vapor phase reaction method, a method of pyrolysing magnesium hydroxide, and an electro-fusing method. In particular, as a method of preparing a magnesium oxide fine powder, there have been known a vapor phase reaction method and a pyrolysis method of heat-treating a magnesium hydroxide powder.
Magnesium oxide has heat resistance, electric insulating property, or the like, so that it has been widely used for refractory, magnesia cement, catalyst, absorbent, antiacid, protective layer for dielectric of PDP, etc. The protective layer for the plasma display panel (PDP) has been largely used for providing improved protection of dielectric and luminance efficiency of phosphor using excellent sputtering resistance and high secondary electron emission coefficient of magnesium oxide by forming a magnesium oxide layer on a dielectric layer. It has been recently reported that luminous efficiency of the PDP is increased and discharge characteristics thereof, such as luminance and discharge voltage, etc. are improved.
Korean patent publication No. 2000-0048076 disclosed a method of improving discharge characteristics by preventing or suppressing generation of a hydroxide and a carbonate of magnesium oxide by forming a fluoride layer on the surface of a magnesium oxide protecting film body. This method has a problem in that a further process of forming the fluoride layer after forming the protective layer is needed.
Korean patent publication No. 2000-0006661 disclosed a method of improving discharge characteristics by applying paste containing magnesium oxide single crystal prepared by a vapor phase reaction method with a screen printing method, an offset method, a dispenser method, an inkjet method, or a roll coat method, etc., when compared with a magnesium oxide layer prepared by a conventional deposition method. However, the aforementioned publication does not concretely disclose how to prepare the magnesium oxide powder.
Also, Korean patent publication No. 2007-0083428 disclosed a method of preparing a fluorine-containing magnesium oxide powder by mixing a magnesium oxide powder with a magnesium fluoride powder or firing a magnesium oxide powder at a temperature of at least 850° C. under a fluorine-containing atmosphere in order to prepare the magnesium oxide powder emitting high-efficient ultraviolet ray. This method has a problem in that a post-processing process of the magnesium oxide powder is further needed and it is difficult to uniformly mix the fluorine and the magnesium oxide powder.